The present invention relates to sealing caps primarily intended for use with suction bags used in medical/surgical suction equipment to withdraw body fluids from a patient. Examples of suction equipment provided with bags of this nature are disclosed in my U.S. Pat. Nos.: 3,963,027; 3,982,539; 4,004,590; and 4,135,515. The cap described and claimed herein is an improvement over the cap disclosed in my above-identified patents.
Suction equipment of this type is characterized in that the suction bag is enclosed in a chamber. A tube leads from the patient to the bag so that body fluids withdrawn from the patient may be transferred to the bag. Air is evacuated from the chamber to produce a vacuum. The vacuum is communicated to the interior of the bag by an opening in the bag or by a tube extending from the bag within the chamber. Preferably, and as disclosed in my above-identified patents, the bag has a short tube connected to the upper portion thereof to transfer the suction from the vacuum chamber, through the bag and to the patient. This short tube can also act as a drain spout for the bag. Additionally, it is preferred to provide a cap for the drain spout in which there exists an air gap between the drain spout and the cap for the spout.
This is a significant feature in suction equipment of this type, in that an added safeguard against contamination is obtained by evacuating the air from the chamber and having the resultant vacuum communicated to the inside of the suction bag through a small air passage in a convoluted path similar to the path of a Pasteur flask. In other suction equipment, the air is evacuated directly from the suction bag, so that the suction bag and its contents are in direct communication with a suction or vacuum mechanism. This direct communication of bag and pump increases the chances of contamination in both directions, that is, from the pump through the bag and into the patient or from the contents of the bag through the pump and into the surrounding area.
Previously, another cap was used with this type of suction bag. This prior cap may best be understood by reference to FIGS. 12 and 13 of my U.S. Pat. No. 4,004,590. The drain spout of the bag in that patent is provided with a longitudinal rib, so that when the cap is applied, small air passages remain at each side of the rib. These small leakage passages provide for communication of the vacuum in the chamber to the interior of the bag. A wad of cotton or other similar material may be provided in the cap to act as a filter for contaminants. The cap is removable to permit emptying the bag through the drainage tube.
With these previous caps, the small air passages will always be open. Thus, when the bag is being transported for disposal or analysis, the contents are susceptible of dripping out through the small passage, and some communication with the surrounding atmosphere is allowed by the air passages. This shortcoming increases the possibility of contamination and complicated the task of transporting used bags.